Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

From January 2018 to December 2024, 75% of Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%).

  • Total suspected cases: 40,282
  • Total confirmed cases: 6,030
  • Deaths from Confirmed Cases: 1,105
  • Case Fatality Ratio: 21%
  • Number of Health Care Workers: 233

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all lab confirmed cases in Nigeria was between 16-27% and decreased over time.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • The variation in CFR is likely due to late patient presentation and differences in case management, highlighting the need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 15

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 4,260 suspected cases were reported from 1 in Jigawa, Katsina, Osun to 1,277 in Ondo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 25% decrease in the cumulative number of suspected cases reported.

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 18% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 15, 87% of LF cases are from Ondo (30%), Bauchi (25%), Edo (16%), and Taraba (16%) States.

  • Total confirmed cases: 686

  • Deaths from Confirmed Cases: 129

  • Case Fatality Ratio: 19%

  • Number of Health Care Workers: 21

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 15 2025, cumulatively 686 cases and 129 deaths (CFR=19%) across 18 States have been reported.
  • At same period 2024, a total of 27 States reported at least one confirmed cases.
  • There is a 25% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • There is a 18% decrease in the number of confirmed cases reported in 2025 compared to 2024.
  • In 2024,
    • 36 States had reported at least one suspected case versus 34 States in 2025 to date.
    • 27 States had reported at least one confirmed case versus 18 States in 2025 to date.

Health care worker infections 2020-2025 epiweek 15


  • Top 5 states:
    • 8 HCW infections in Ondo
    • 4 HCW infections in Bauchi
    • 3 HCW infections in Taraba
    • 2 HCW infections in Gombe
    • 1 HCW infections in Ebonyi.

  • As of epi week 15 of 2025, there has been 21 healthcare workers infected, that is 3% of confirmed cases.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 15)

Lassa fever in Ondo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ondo as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 1277 205 27 13%
2024 1180 199 13 7%
2023 1209 283 31 11%
2022 668 206 36 17%
2021 296 69 19 28%
2020 519 310 44 14%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ondo State reported 205 confirmed cases including 27 deaths (CFR 13%).
  • Compared to same period 2024, this represents:
    • 8% increase in the number of suspected cases.
    • 3% increase in the number of confirmed cases.
    • 102% increase in CFR.




  • In 2024 as of week 15:
    • 1180 in the number of suspected cases.
    • 199 in the number of confirmed cases.
    • 13 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 15:
    • 1209 in the number of suspected cases.
    • 283 in the number of confirmed cases.
    • 31 in the number of deaths.
    • 11% average CFR.




  • In 2022 as of week 15:
    • 668 in the number of suspected cases.
    • 206 in the number of confirmed cases.
    • 36 in the number of deaths.
    • 17% average CFR.




  • In 2021 as of week 15:
    • 296 in the number of suspected cases.
    • 69 in the number of confirmed cases.
    • 19 in the number of deaths.
    • 28% average CFR.




  • In 2020 as of week 15:
    • 519 in the number of suspected cases.
    • 310 in the number of confirmed cases.
    • 44 in the number of deaths.
    • 14% average CFR.

Lassa fever in Bauchi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Bauchi as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 759 174 12 7%
2024 675 139 28 20%
2023 654 98 18 18%
2022 625 114 12 11%
2021 42 8 2 25%
2020 268 43 19 44%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Bauchi State reported 174 confirmed cases including 12 deaths (CFR 7%).
  • Compared to same period 2024, this represents:
    • 12% increase in the number of suspected cases.
    • 25% increase in the number of confirmed cases.
    • 66% decrease in CFR.




  • In 2024 as of week 15:
    • 675 in the number of suspected cases.
    • 139 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 20% average CFR.




  • In 2023 as of week 15:
    • 654 in the number of suspected cases.
    • 98 in the number of confirmed cases.
    • 18 in the number of deaths.
    • 18% average CFR.




  • In 2022 as of week 15:
    • 625 in the number of suspected cases.
    • 114 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 11% average CFR.




  • In 2021 as of week 15:
    • 42 in the number of suspected cases.
    • 8 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 25% average CFR.




  • In 2020 as of week 15:
    • 268 in the number of suspected cases.
    • 43 in the number of confirmed cases.
    • 19 in the number of deaths.
    • 44% average CFR.

Lassa fever in Edo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Edo as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 1249 108 17 16%
2024 1368 185 24 13%
2023 1666 250 31 12%
2022 1247 177 24 14%
2021 939 108 12 11%
2020 1123 320 39 12%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Edo State reported 108 confirmed cases including 17 deaths (CFR 16%).
  • Compared to same period 2024, this represents:
    • 9% decrease in the number of suspected cases.
    • 42% decrease in the number of confirmed cases.
    • 21% increase in CFR.




  • In 2024 as of week 15:
    • 1368 in the number of suspected cases.
    • 185 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 13% average CFR.




  • In 2023 as of week 15:
    • 1666 in the number of suspected cases.
    • 250 in the number of confirmed cases.
    • 31 in the number of deaths.
    • 12% average CFR.




  • In 2022 as of week 15:
    • 1247 in the number of suspected cases.
    • 177 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 14% average CFR.




  • In 2021 as of week 15:
    • 939 in the number of suspected cases.
    • 108 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 11% average CFR.




  • In 2020 as of week 15:
    • 1123 in the number of suspected cases.
    • 320 in the number of confirmed cases.
    • 39 in the number of deaths.
    • 12% average CFR.

Lassa fever in Taraba State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Taraba as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 281 108 31 29%
2024 210 96 20 21%
2023 230 81 28 35%
2022 77 31 14 45%
2021 52 18 11 61%
2020 101 55 21 38%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Taraba State reported 108 confirmed cases including 31 deaths (CFR 29%).
  • Compared to same period 2024, this represents:
    • 34% increase in the number of suspected cases.
    • 12% increase in the number of confirmed cases.
    • 38% increase in CFR.




  • In 2024 as of week 15:
    • 210 in the number of suspected cases.
    • 96 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 21% average CFR.




  • In 2023 as of week 15:
    • 230 in the number of suspected cases.
    • 81 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 35% average CFR.




  • In 2022 as of week 15:
    • 77 in the number of suspected cases.
    • 31 in the number of confirmed cases.
    • 14 in the number of deaths.
    • 45% average CFR.




  • In 2021 as of week 15:
    • 52 in the number of suspected cases.
    • 18 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 61% average CFR.




  • In 2020 as of week 15:
    • 101 in the number of suspected cases.
    • 55 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 38% average CFR.

Lassa fever in Ebonyi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ebonyi as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 148 21 11 52%
2024 241 43 24 56%
2023 189 50 28 56%
2022 191 39 18 46%
2021 80 15 6 40%
2020 188 73 21 29%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ebonyi State reported 21 confirmed cases including 11 deaths (CFR 52%).
  • Compared to same period 2024, this represents:
    • 39% decrease in the number of suspected cases.
    • 51% decrease in the number of confirmed cases.
    • 6% decrease in CFR.




  • In 2024 as of week 15:
    • 241 in the number of suspected cases.
    • 43 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 56% average CFR.




  • In 2023 as of week 15:
    • 189 in the number of suspected cases.
    • 50 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 56% average CFR.




  • In 2022 as of week 15:
    • 191 in the number of suspected cases.
    • 39 in the number of confirmed cases.
    • 18 in the number of deaths.
    • 46% average CFR.




  • In 2021 as of week 15:
    • 80 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2020 as of week 15:
    • 188 in the number of suspected cases.
    • 73 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 29% average CFR.

Lassa fever in Kogi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Kogi as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 65 15 4 27%
2024 108 28 2 7%
2023 38 11 1 9%
2022 102 40 7 18%
2021 5 1 0 0%
2020 84 35 8 23%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Kogi State reported 15 confirmed cases including 4 deaths (CFR 27%).
  • Compared to same period 2024, this represents:
    • 40% decrease in the number of suspected cases.
    • 46% decrease in the number of confirmed cases.
    • 273% increase in CFR.




  • In 2024 as of week 15:
    • 108 in the number of suspected cases.
    • 28 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 15:
    • 38 in the number of suspected cases.
    • 11 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 9% average CFR.




  • In 2022 as of week 15:
    • 102 in the number of suspected cases.
    • 40 in the number of confirmed cases.
    • 7 in the number of deaths.
    • 18% average CFR.




  • In 2021 as of week 15:
    • 5 in the number of suspected cases.
    • 1 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 15:
    • 84 in the number of suspected cases.
    • 35 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 23% average CFR.

Lassa fever in Gombe State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 64 14 7 50%
2024 25 3 1 33%
2023 32 6 0 0%
2022 111 17 7 41%
2021 3 0 0 –
2020 28 7 2 29%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 14 confirmed cases including 7 deaths (CFR 50%).
  • Compared to same period 2024, this represents:
    • 156% increase in the number of suspected cases.
    • 367% increase in the number of confirmed cases.
    • 50% increase in CFR.




  • In 2024 as of week 15:
    • 25 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 33% average CFR.




  • In 2023 as of week 15:
    • 32 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2022 as of week 15:
    • 111 in the number of suspected cases.
    • 17 in the number of confirmed cases.
    • 7 in the number of deaths.
    • 41% average CFR.




  • In 2021 as of week 15:
    • 3 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 15:
    • 28 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.

Lassa fever in Benue State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Benue as of week 15:
Years Suspected cases Confirmed cases Deaths CFR
2025 63 9 4 44%
2024 1040 62 11 18%
2023 142 36 3 8%
2022 190 31 8 26%
2021 16 4 0 0%
2020 27 8 3 38%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Benue State reported 9 confirmed cases including 4 deaths (CFR 44%).
  • Compared to same period 2024, this represents:
    • 94% decrease in the number of suspected cases.
    • 85% decrease in the number of confirmed cases.
    • 151% increase in CFR.




  • In 2024 as of week 15:
    • 1040 in the number of suspected cases.
    • 62 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 18% average CFR.




  • In 2023 as of week 15:
    • 142 in the number of suspected cases.
    • 36 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 8% average CFR.




  • In 2022 as of week 15:
    • 190 in the number of suspected cases.
    • 31 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 26% average CFR.




  • In 2021 as of week 15:
    • 16 in the number of suspected cases.
    • 4 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 15:
    • 27 in the number of suspected cases.
    • 8 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 38% average CFR.

Thank you

Any questions or suggestions? Contact us: Anaïs Legand and Antoine Chaillon